What phraseology is used to assign a beacon code to an aircraft?

The appropriate phraseology used to assign a beacon code to an aircraft is "Squawk." This term is commonly used in air traffic control communications to instruct pilots to set their transponders to a specific four-digit code. When an air traffic controller tells a pilot to "squawk" a particular code, it indicates that the pilot should enter the given code into the aircraft's transponder. This enables the aircraft to be identified on radar, enhancing situational awareness for both pilots and air traffic controllers.

Other options do not align with standard aviation communication practices. While "Change Code," "Set Code," and "Code Assign" may seem intuitive, they are not the terminology recognized or used in official ATC phraseology. Hence, "Squawk" is the correct term that ensures clarity and consistency in communications.